Preheat the oven to 200C/400F/Gas 6. In a roasting tray, toss together the pumpkin with the fresh chillies, cumin, chilli flakes, salt and pepper and all but one tablespoon of the olive oil. Roast for 30 minutes, turning over about half way through, until the pumpkin has caramelised. Leave to cool slightly.
Heat the remaining tablespoon of olive oil in a frying pan and lightly wilt the pak choi for a minute or so, then put them in a serving dish to cool slightly.
To make the dressing, whisk the vinegar and olive oil together in a bowl, then add the spring onions and season with salt and pepper.
Scatter the pumpkin, baby spinach and olives over the pak choi leaves, mix them lightly, then scatter over the crumbled goats’ cheese (if using) and drizzle the dressing on top.
Serve the salad with slices of a bread with a filling, such as a savoury brioche couronne.